COVID-19 vaccines developed by Pfizer and Moderna apparently offer significantly less antibody protection against the highly contagious variant that originated in South Africa, new studies show.
The studies, published in the New England Journal of Medicine on Wednesday, indicated that both vaccines elicit much lower levels of neutralizing antibodies against the new strain compared to the initial SARS-CoV-2 virus.
For the Pfizer study, scientists developed a manufactured virus that contains the same mutations that occur at the peak portion of the South African variant, known as B.1.351.
Researchers tested the engineered virus against blood taken from people who received the vaccine.
They found that the level of neutralizing antibodies decreased by two-thirds compared to the performance it did with the most common version of the virus in U.S. trials.
However, it is unclear whether the reduced antibody response will render the vaccine ineffective against the strain, as it is not known what level is needed to neutralize the virus.
‘We do not know what the minimum neutralizing number is. We do not have the cut-off point, ”said Pei-Yong Shi, co-author of the study.
Meanwhile, the Moderna study found a six-fold decrease in antibody response to the vaccine variant.
The results were published as part of a letter from the Massachusetts-based company in the same journal.
But researchers have also warned that the effectiveness of the Moderna vaccine against the strain is not yet known.
The company said earlier that it believes the vaccine provides protection against the variant.
According to the Centers for Disease Control and Prevention, there are currently 19 cases of B.1.351 reported in the United States in 10 states.
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